Th long-term goal of this research is to determine the three-dimensional structures of M-components. The source of the immunoglobulins and immunoglobulin fragments, whose crystal structures will be determined by X-ray diffracton, will be patients with monoclonal gammopathies. Most often these will be malignancies involving myelomatosis, Waldenstrom's macroglobulinemia, or cryoglobulinemia. M-components associated with benign monoclonal gammopathies will be studied whenever possible also in order to compare them with proteins from cancer patients. A continuous search, now in progress, will be maintained to find proteins that yield good quality single crystals. The proposed research could lead to a better understanding of cryoprecipitation phenomena, and it could provide information concerning pathogenesis of M-components. It will also add to our knowledge of the molecular structures and the mechanisms of action of antibodies.